90 Minute Timer

This page is set to 1 hour 30 minutes: 1 in Hours and 30 in Minutes, which is 5,400 seconds.

1. Check the display. It reads 01:30:00, because a countdown of an hour or more shows hours, minutes and seconds.
2. Change the three boxes, Hours, Minutes and Seconds, if your block is a little different. A film listed at 1 hour 52 minutes needs 1 and 52.
3. Put a name in Label (optional), for example Study or Film night, so the finish message tells you what ended.
4. Tick Play a sound when time is up if you want the alarm, then press Start. The button changes to Pause.
5. Press Resume after a pause, Reset to go back to 01:30:00, or Full screen to turn the page into a large wall clock.

Press Space to start or pause, and R to reset when the timer is stopped, provided the cursor is outside a text box.

Because 90 minutes is a long run, it is worth testing the sound once. Set Hours and Minutes to 0 and Seconds to 5, tick the sound option, press Start and listen. Then type 1 and 30 back into Hours and Minutes and set Seconds to 0 while the clock is stopped.

Ninety minutes is often quoted as the average length of one sleep cycle, the pattern of lighter and deeper sleep that repeats through the night. It is an approximation: the length varies from person to person and across a night, so treat it as a rough planning figure and not a rule. Counting in 90 minute units gives a quick way to talk about how long a night is:

As an illustration, five cycles starting at 11:00 pm would end at 6:30 am, though falling asleep takes some time too. This is general information and not medical advice. If you have trouble sleeping, a health professional is the right person to ask.

This page counts a 90 minute period, and it is not a sleep tracker. It cannot know when you fall asleep, and it is not built to wake you. Use your phone alarm clock for anything that matters, because the timer rings only while the page is open. To add several periods to a start time, the time calculator adds durations such as 5 x 1:30.

A long block is easier to plan when you decide where the pause goes. Ninety minutes of concentration is demanding for most people, so one option is two blocks of 45 with a short rest between them, which you can time with the 45 minute timer. Another is 60 minutes of work and a 30 minute wind-down for notes, with the 60 minute timer for the first part.

For a double lesson, a 90 minute film segment or a long workshop, the single countdown plus the progress bar shows how much remains. At the halfway point the display reads 45:00, and at three quarters it reads 22:30. That is simpler than doing sums while teaching or watching.

• Decimal hours. An hour and a half is 1.5 hours, or 5,400 seconds. The time converter checks other conversions.
• One alarm only. It plays four tones for just over a second and does not repeat, so stay within hearing distance.
• The page must stay open. Closing the tab ends the count, and a locked phone may stop the sound.
• Power. On a laptop, check that it will not sleep before the 90 minutes are up.

To find out how long a real task takes, count up with the online stopwatch first and then set this timer.

Films and shows have their own run times, so check the listing and type that length. Add a few minutes for trailers if a screening starts late, because the timer counts from the moment you press Start and cannot know when the picture actually begins.